The average US temperature has increased about 1.8C since the start of the 20th century. That temperature rise has disproportionately impacted low-lying populations of south-east Asia, South America and the Caribbean.
Satellite imagery of clouds covering the Earth shows several unusual patterns during the past three decades. Specifically, more intense atmospheric blackouts occur in the subtropics and tropics, (18%, 44% and 52% respectively) compared to higher latitudes. Blackouts are accompanied by stronger monsoons in the tropics, and reduced solar output in the tropics (4% and 27%).
Both trend lines are negative, indicating a negative feedback loop between global warming and weather variability.
Humans are changing the pattern of rainfall (some rain is heavier or more intense than expected) with increasing average temperatures. A strong monsoon runs from the Atlantic to the Indian Ocean with relative ease on average (11-30 days), but the period of uncertainty depends on the size of the tropical rainfall zone. It is the disappearance of monsoon behavior in the subtropics and tropics (such as hurricanes, typhoons, or heavy rains) which are now predicted to become much more frequent and intense because of climate change.
If this new pattern of the global climate is true, the Global Earth Observation Programme (GEO) may be more likely to record two to four new blackouts per month, perhaps 6 months per year. This could signal a major change in meteorological patterns in global and regional averages.
The alignment of blackouts with warming temperatures may be most evident in the south-east Asia basin, the traditional land-based systems of rain and snow, which serve to rain more or snow more gradually, and is sensitive to rising temperatures in the tropics. The tropics are responsible for up to 80% of the global average temperature.
The shift of monsoon patterns toward the higher latitudes (and away from the subtropics) is likely to occur throughout the global climate system, with implications for agriculture and socio-economic stability across the globe.
If global warming increases the probability of blackouts by 1.8C, that would translate into an extra 15,000-50,000 hours of blackouts in the US every year. Of all the international cloud patterns in the atmosphere, blackouts are certainly the most sensitive to warming temperatures. And blackouts are expected to become more frequent and intense as temperatures increase.
If global warming increases the probability of blackouts by 1.8C, that would translate into an extra 15,000-50,000 hours of blackouts in the US every year.
So how do we avoid flooding, heat waves, etc in the tropics and subtropics? Climate models do not depict a smooth pathway through the climatic system, but instead have deep peaks, troughs and valleys. The warming climate with which we are living is likely to disrupt that climate and of course, this time will be made even more intense by the major fires, heat waves and storms the last few years and the “Great Super Bloom” of 2017. Even if a single intensity-caused blackout occurred, expect a significant amount of turbulence with a split-second delay between events. This increased lag between blackouts and weather generally has significance for disaster response and insurance.
And while we can mitigate the total amount of warming, the impact of each excess heating-caused blackout can only be managed by slowing or delaying global warming as much as possible (and this is extremely hard to do).
We need to be able to cope with blackouts – but it will be up to us to adapt our vulnerability to those events to the changes being caused by climate change.